Accumulated Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	$ 1,732		$ 1,732			$ 1,504
Accumulated other comprehensive income, net of tax, end of period	1,732		1,732			1,504
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated unrealized gains, net, on investments available for sale, before tax, beginning of period	2,452	2,231	2,335	1,875
Other comprehensive income before reclassification, before tax	252	(230)	387	164
Reclassification adjustment for realized gains, net, included in net income, before tax	(17)	(14)	(35)	(52)
Effect on other comprehensive income, before tax	235	(244)	352	112
Accumulated unrealized gains, net, on investments available for sale, before tax, end of period	2,687	1,987	2,687	1,987
Accumulated Other Comprehensive Income Loss Tax [Abstract]
Accumulated unrealized gains, net, on investments available for sale and other invested assets, tax, beginning of period	931	686	931	686
Other comprehensive income before reclassification, tax	87	(81)	135	56
Reclassification adjustment for realized gains, net, included in net income, tax	(5)	(4)	(12)	(17)
Effect on other comprehensive income, tax	82	(85)	123	39
Accumulated unrealized gains, net, on investments available for sale and other invested assets, tax, end of period	849	771	808	647
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated unrealized gains, net, on investments available for sale and other invested assets, net of tax, beginning of period	1,603	1,460	1,527	1,228
Other comprehensive income before reclassification , net of tax	165	(149)	252	108
Reclassification adjustment for realized gains, net, included in net income, net of tax	(12)	(10)	(23)	(35)
Effect on other comprehensive income, net of tax	153	(159)	229	73
Accumulated unrealized gains, net, on investments available for sale and other invested assets, net of tax, end of period	1,756	1,301	1,756	1,301
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Other comprehensive income before reclassification, before tax	0		0	0
Accumulated unrealized losses, net, for pension obligations, before Tax, beginning of period	(19)	(99)	(18)	(101)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Amortization of Actuarial Gain (Loss) and Prior Service Cost, before Tax	0	3	(1)	5
Effect on other comprehensive income, before tax	0	3	(1)	5
Accumulated unrealized losses, net, for pension obligations, before Tax, end of period	(19)	(96)	(19)	(96)
Accumulated Other Comprehensive Income Loss Tax [Abstract]
Other comprehensive income before reclassification, tax	0	0	0	0
Accumulated unrealized losses, net, for pension obligations, tax, beginning of period	(6)	(34)	(6)	(35)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Amortization of Actuarial Gain (Loss) and Prior Service Cost, Tax	0	1	0	2
Effect on other comprehensive income, tax	0	1	0	2
Accumulated unrealized losses, net, for pension obligations, tax, end of period	(6)	(33)	(6)	(33)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other comprehensive income before reclassification , net of tax	0	0	0	0
Accumulated unrealized losses, net, for pension obligations, net of tax, beginning of period	(13)	(65)	(12)	(66)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Amortization of Actuarial Gain (Loss) and Prior Service Cost, Net of Tax	0	2	(1)	3
Effect on other comprehensive income, net of tax	0	2	(1)	3
Accumulated unrealized losses, net, for pension obligations, net of tax, end of period	(13)	(63)	(13)	(63)
Accumulated Net Unrealized Gain (Loss) on Deferred Costs, Reserves And Other
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Other comprehensive income before reclassification, before tax	(2)	27	1	27
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, before tax, beginning of period	(17)	(50)	(16)	(50)
Other Comprehensive Income (Loss), Reclassification Adjustment for Life Deferred Acquisition Costs, Life Policy Reserves and Other, Before Tax	3	(3)	(1)	(3)
Effect on other comprehensive income, before tax	1	24	0	24
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, before tax, end of period	(16)	(26)	(16)	(26)
Accumulated Other Comprehensive Income Loss Tax [Abstract]
Other comprehensive income before reclassification, tax	0	10	1	10
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, tax, beginning of period	(5)	(17)	(5)	(17)
Other Comprehensive Income (Loss), Reclassification Adjustment for Life Deferred Acquisition Costs, Life Policy Reserves and Other, Tax	0	(2)	(1)	(2)
Effect on other comprehensive income, tax	0	8	0	8
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, tax, end of period	(5)	(9)	(5)	(9)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other comprehensive income before reclassification , net of tax	(2)	17	0	17
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, beginning of period, net of tax	(12)	(33)	(11)	(33)
Other Comprehensive Income (Loss), Reclassification Adjustment for Life Deferred Acquisition Costs, Life Policy Reserves and Other, Net of Tax	3	(1)	0	(1)
Effect on other comprehensive income, net of tax	1	16	0	16
Accumulated unrealized losses, net, on life deferred acquisition costs, life policy reserves and other, end of period, net of tax	(11)	(17)	(11)	(17)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before taxes, beginning of period	2,416	2,082	2,301	1,724
Change in unrealized gains, net, on investments available for sale, before Tax	235	(244)	352	112
Change in pension obligations, before tax	0	3	(1)	5
Change in life deferred acquisition costs, life policy reserves and other, before Tax	1	24	0	24
Effect on other comprehensive income, before Tax	236	(217)	351	141
Accumulated other comprehensive income, before taxes, end of period	2,652	1,865	2,652	1,865
Accumulated Other Comprehensive Income Loss Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	838	720	797	595
Change in unrealized gains, net, on investments available for sale and other invested assets, tax	82	(85)	123	39
Change in pension obligations, tax	0	1	0	2
Change in life deferred acquisition costs, life policy reserves and other, tax	0	8	0	8
Effect on other comprehensive income, tax	82	(76)	123	49
Accumulated other comprehensive income, tax, end of period	920	644	920	644
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	1,732	1,221	1,732	1,221	1,578	1,504	1,362	1,129
Change in unrealized gains, net, on investments available for sale, net of tax	153	(159)	229	73
Change in pension obligations, net of tax	0	2	(1)	3
Change in life deferred acquisition costs, life policy reserves and other, net of tax	1	16	0	16
Effect on other comprehensive income, net of tax	154	(141)	228	92
Accumulated other comprehensive income, net of tax, end of period	$ 1,732	$ 1,221	$ 1,732	$ 1,221	$ 1,578	$ 1,504	$ 1,362	$ 1,129